


Exorcist, Demonologist, Witch, and Avenger

by magicforever39



Category: Constantine (TV), Harry Potter - J. K. Rowling, The Avengers (Marvel Movies)
Genre: F/M
Language: English
Status: In-Progress
Published: 2017-01-09
Updated: 2017-01-12
Packaged: 2018-09-15 21:41:10
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 4,389
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/9258380
Author URL: https://archiveofourown.org/users/magicforever39/pseuds/magicforever39
Summary: Ariadne Black is Sirius and Regulus's younger sister. She joined S.H.I.E.L.D. and the Avengers after being forced to cut off all contact with people from her old life, including her boyfriend, John Constantine. After dealing with Strucker and Ultron, her past catches up to her at the same time that Lord Voldemort returns.  When things go wrong for Ariadne, they tend to happen all at once.





	1. Sokovia to Mexico

**Author's Note:**

> Summary isn't my greatest, but essentially this story is a Harry Potter and Avengers crossover with characters and elements from the Constantine TV show. This story takes place during and after Age of Ultron, after the events of season 1 of Constantine, and before and during The Order of the Phoenix. Characters will be added as I think of them or as they come up.

Ariadne groaned and tried to figure out why her body felt so heavy. The last thing she remembered was boarding a civilian flight to Tokyo. She forced her eyes open and saw the smirking face of Baron von Strucker.  
“Welcome to Sokovia, Agent Black,” Strucker said.  
Ariadne sat up, well tried anyway. She swore violently when she realized she was strapped to a metal table. Her grey eyes flicked to Strucker and they narrowed in dawning comprehension. “You’re Hydra.”  
“One side of a coin that is no longer currency along with S.H.I.E.L.D.,” Strucker said. “If you’re hoping for a rescue from Captain America and the rest of your colorful friends, it won’t happen.”  
“You are seriously underestimating them, you bastard,” Ariadne spat.  
“Perhaps, but by the time they figure out what happened to you it will be too late,” a man in a lab coat said as he entered the room.  
“Quite right, Dr. Lisk,” Strucker said. “You see, Agent Black, today you are going to become part of something bigger than yourself.”  
Ariadne tried to avoid Dr. Lisk hooking tubes and electrodes up to her body but the bindings prevented it. She paled when she saw that she was now attacked to Loki’s scepter.  
“Mind control? Really, Strucker?” she sneered. “That crap won’t work on me.”  
“Oh, mind control is just the surface of what the scepter can do,” Strucker said. “We’ve found it can do something so much more advanced. Welcome to the new world, Agent Black.”  
Dr. Lisk started the procedure and Ariadne felt pain stronger than she’d been subjected to in years. Within seconds her clothes were drenched in sweat. She screamed as she felt as though every molecule in her body was being ripped apart.  
The next moment the pain vanished leaving Ariadne feeling weightless. She opened her eyes to see an unfamiliar dirty ceiling. Shifting, she found she was no longer bound or hooked up to any machines. She rolled off the counter she was lying on and landed in a crouch behind it. As she looked around, Ariadne was confused to see signs on the walls saying, “No Fumar.” The Spanish was out of place since Russian was the official language of Sokovia.  
Ariadne stood up. As she looked around she heard a familiar voice saying, “So what’s the new plan, John?” She turned around to see Chas Chandler staring at her in shock from the gurney he was sitting on.  
“There’s no new plan mate,” John answered. He noticed Chas had stopped paying attention and was staring at something at the other end of the room. He craned his head to see what had stunned both Chas and Anne-Marie and when he did, he froze.  
“I know it’s been a long time,” Ariadne said, trying to remain calm. She stepped toward the other three and found herself next to John Constantine. “Well that was disconcerting. Anyway, where are we and why are you wearing a nun’s habit Anne-Marie?”  
“We’re in a Mexican prison and I joined a nearby convent,” Anne-Marie said.  
“How are you here, Ari?” Chas asked.  
“No idea,” Ariadne said. She looked down at the man she hadn’t seen in over four years. “You look like crap, John.”  
“You’re not looking so hot yourself, Aria,” John replied with a weak chuckle.  
Ariadne shook her head slightly and in doing so noticed a brand on his arm. She went to touch it and cursed when her fingers went through his arm. She closed her eyes and took a deep breath. When she tried again, she could rest her fingers just underneath the mark. John’s forearm twitched under her touch and he moved his hand as though to hold hers again.  
“You always were good at adapting, luv,” John said, smiling.  
“Why do you have the symbol for the demon king Pazuzu seared onto your arm?” Ariadne asked, her tone brokering no room for bullshit.  
“Because the bloody demon is inside me.”  
“How?”  
“I cast off my spiritual protections and invited it in.”  
“Why would you do something as idiotic as that?”  
“It was the only way I could survive a hungry Invunche attack,” John explained.  
After Ariadne finished swearing Chas could pitch in, “He was also dealing with being shot in the chest.”  
“What?” Ariadne asked. Her voice turned dangerous even though her eyes flickered over John’s chest in worry.  
“He threatened the life of an infant,” Anne-Marie said. “He would have sacrificed it without blinking. So, when the choice was mine, I chose to sacrifice him instead.”  
John flinched at her words but then grew nervous when he felt Ariadne’s fingers disappear from his arm. The handcuffs prevented him from attempting to hold her back.  
“So, you shot him?” Ariadne asked. Her voice took on an icy quality that Chas and Anne-Marie didn’t recognize but John did from when she learned about Pettigrew’s betrayal of their friends. “It didn’t occur to you that John’s ‘threats’ were maybe just bluffs. John wouldn’t sacrifice an innocent.”  
“Defending him like always,” Anne-Marie said. “You’ve been dead for over four years, Ariadne. People change, if it’s escaped your notice.”  
Ariadne stiffened as did John behind her. “That was uncalled for Anne-Marie,” Chas said.  
“You don’t think I know that?” Ariadne hissed, fists clenching. “I don’t always defend John. There are several idiotic things he’s done that I don’t condone, getting himself possessed by a demon king is one of them. But, Anne-Marie, don’t ever, ever presume to know what I understand. I know people can change as I’ve seen it firsthand.”  
“Uh, Aria luv you might want to calm down before you burn down the building with us in it,” John said. At her confused look, he gestured at her arms.  
Ariadne looked down to see her arms wreathed in flames. “Well that’s new,” she muttered, wondering if it was the scepter that caused it or because she was currently a spirit. In the past, she could only summon regular fire to her hands. She took a couple deep breaths and the flames died down. Shooting one last glare at Anne-Marie, Ariadne moved back to John’s side. She rested one hand on his shoulder and held his hand in her other. His grip was tight, both from the strain of keeping Pazuzu down and because he didn’t want Ariadne to disappear.  
“So, how are you going to get the demon out of John?” Ariadne asked. “Exorcism?”  
“There’s no time for a straight up exorcism, luv,” John told her.  
“What about the mill house?” Anne-Marie asked him opting to ignore Ariadne. “Jasper’s defenses might weaken the entity enough for the ritual to work.”  
“That might work,” Chas said standing up, “but even if we could get John out of here, that’s a twenty-four-hour drive.”  
“Ah, I’d never make it,” John said, gritting his teeth. “This demon’s ready to claw its way out.”  
Ariadne rubbed his shoulder wishing she could lend him some strength or find a way to get the demon out.  
“Unless we can slow it down,” Anne-Marie said. “Look for sedatives, sleeping pills.” She and Chas started going through cupboards.  
“That’s the right idea, but it’s the wrong does,” John said. He had Chas find a guy named Julio.  
Turns out John’s idea of the right dose was heroin. Lots of it. Ariadne looked up as the door opened.  
“You found him,” Anne-Marie said. “Does he have what we need?”  
“Yeah,” Chas said. “Once the prisoners found out it was for John, they became a coalition of the willing.”  
“I’m going to want that story later,” Ariadne told John, prompting him to chuckle.  
“How much were you able to get your hands on?” John asked Julio. He dumped his bag out onto the table.  
“That’s enough heroin to kill a herd of elephants,” Chas said.  
“Well, let’s hope it’s enough to tamp down a bloody Pazuzu,” John groaned.  
Chas stepped out of the room and Julio started cooking up the drugs.  
Ariadne stroked the back of John’s hand with her thumb trying to provide some comfort. “Are you sure you can do this?” she asked him.  
“If there’s anything I’ve learned in the last forty-eight hours, it’s that this demon needs me alive.”  
“And if you’re wrong?” Anne-Marie asked.  
“Well, then, I’ll go out riding the world’s greatest high,” John said, smirking. “With my true love at my side.” He smiled at Ariadne and squeezed her hand. “There are worse ways to meet your maker, eh? It’d be nice if we could be together again, Aria luv, but I doubt that’s going to happen.”  
“You’ve become sappy,” Ariadne said, her eyes glistening with tears.  
Chas walked back in dressed in a lab coat. “Alright, let’s get him out of here.”  
Ariadne moved away from John’s shoulder so Anne-Marie could step in to hold him down.  
“No time like the present,” John said. He turned to Julio. “Do it.”  
Julio filled a syringe with the heroin. Before he was injected, John looked at Ariadne and squeezed her hand gently. “See you in hell, lunático,” Julio said as he injected the heroin into John’s arm.  
John trashed and groaned as the demon tried to fight the effects of the drugs. The heroin won and John’s body relaxed.  
Ariadne breathed a sigh of relief as Chas handed Anne-Marie a lab coat and said, “Now time for phase two.” Anne-Marie nodded and left to change as Ariadne brushed her fingers through John’s sweaty hair.  
Chas looked at his old friend. “It’s good to see you again, Ari, though I wish it was under better circumstances.”  
“Same here,” Ariadne said, squashing her feelings of guilt. “Where are you guys going?”  
“The Mill House, just outside of Atlanta,” Chas said. “But I don’t know if you’d be able to get in. Jasper put some strong defenses around it.”  
Ariadne smirked. “Well it never hurts to try. I’ve always been stubborn.” She looked down at John. “If I can’t, Chas, could you-” Her pain shone through her eyes.  
“I’ll tell him,” Chas promised, knowing what she was trying to ask.  
“Thank you,” Ariadne whispered. She pressed a soft kiss to John’s clammy forehead with a faint murmur, “I’m sorry.” She closed her eyes and disappeared from the room.  
Opening her eyes, Ariadne was greeted by the sight of a mill house surrounded by trees. She stepped forward but found her way blocked by an invisible force.  
“Alright, if that’s the way you want to play it, Jasper,” Ariadne muttered. “I will be getting in though.”  
She glared at the building after she’d seen Chas and the others arrive. “Damn Jasper, you really know your stuff. Though I would’ve thought you’d let your friends in. Even if they were spirits.” She smacked her forehead as she came to a sudden realization. She spread her arms with her palms up and chanted, “I, Ariadne Guinevere Black, am a friend to this millhouse and its occupants.”  
Ariadne took a tentative step forward and smirked when there was no resistance. She hurried into the house and saw the exorcism already under way. She stayed back so she didn’t distract Anne-Marie from the ritual.  
“Go back to hell, beast!” Anne-Marie cried, throwing holy water on a thrashing John. “Back to the filth that spawned you! This one is not yet ready for your embrace. Forgive him his trespasses, Lord, and protect your servant from this abomination. Return to hell and the fiery pit where you belong!”  
The demon bellowed once more before John stopped thrashing, a tendril of black smoke exiting his mouth.  
Ariadne moved to John’s side calling his name.  
Anne-Marie asked, “John, are you alright?”  
Ariadne looked at her. “He just had a demon king exorcized from his body. He won’t be alright.” She turned back to a still John. “Answer us you wanker.”  
John groaned, “Keep your hair on. I’m far from alright but I’m free of it. When’d you get here?”  
“Just now,” Ariadne said, smiling. “I’ve got to hand it to Jasper. He did a great job with the defenses around this place.”  
“How’d you get in?” Chas asked.  
“I told the wards that I was a friend. Of course, that was after I spent the last twenty-four hours trying to find a way through them.”  
“You are seriously stubborn,” Chas said. He shook his head.  
“I don’t know about you lot,” John said, “but I could murder a bloody drink.” Ariadne laughed and rested her hand right over his heart.  
Zed noticed and was going to say something but Chas stopped her.  
Anne-Marie untied John and he sat up staring at Ariadne.  
“I’m sorry,” he murmured.  
“What for?” Ariadne asked confused.  
“It was my fault,” John said keeping his voice low enough that their conversation didn’t reach the others.  
Ariadne realized what he was talking about. “Damn it, John, my death was not your fault. None of us knew that demon was that powerful or that it would get a lucky shot in. You need to stop blaming yourself.”  
John was going to say something more but noticed her starting to flicker. “Damn luv, it seems like your time here is done.  
She sighed. “It looks like it.” She pressed a lingering kiss to John’s cheek. “I love you, John.” She disappeared before John could reply.  
“Who was that?” Zed asked Chas when John left the room.  
“Ariadne Black,” he said. “She was a good friend and she and John were together when she died over four years ago.”  
“How long were they dating?”  
“I’m not entirely sure. It was serious enough that most of us in the group had a betting pool for when John would take the next step.” Zed stared at him in shock. “Yeah it’s surprising if you didn’t see them. Ariadne is a sore spot of John so don’t tell him I told you.” Zed nodded.  
After Anne-Marie left to return to Mexico, John sat in his room, a photo album open in his lap. Images of himself and Ariadne stared up at him, some still and others moved showing the two of them laughing or replaying whatever they were doing when the photos were taken.  
“I miss you, Aria,” John breathed. He brushed his fingers over one of the pictures. “I’ve never stopped loving you.”


	2. Meet the Other Guinea Pigs

Ariadne woke up to see Dr. Lisk standing over her. “You survived. Excellent,” he said.  
“It seems the experiment was successful,” Strucker said. “At least if what happened when she was unconscious was any indication.”  
Ariadne groaned and told them to go do something that was anatomically impossible. She was yanked to her feet by a pair of Hydra foot soldiers. They marched her down a series of halls until they reached a cell door.  
She was handed a change of clothes consisting of a tank top, sweatshirt and a pair of sweatpants. The goon shoved her into the room. She turned glare at Strucker.  
“Welcome to your new living quarters, Phoenix,” Strucker said.  
The door slammed shut as Ariadne bit out a string of curses. She was cut off by a silver and blue blur slamming her into the wall. Once she got over her surprise, she found herself staring at a young man with silver and brown hair.  
“You’re one of the Avengers,” he said, blue eyes flashing in anger. A girl who looked enough like him that Ariadne figured she had to be a sibling or related somehow.  
Ariadne managed to find the strength to shove him off. “So?” she asked, massaging her throat. Her legs buckled and she slid down the wall. “I help protect the world from evil megalomaniacs, the occasional sludge monster, and aliens. So, sue me. Anyway, sod off and leave me to my dismal thoughts and pain.”  
“And let you plot how to attack us?” the girl asked. “No way.” Red energy gathered around her hands.  
“You honestly think I’d attack when I can’t even stand?” Ariadne asked. “Besides I don’t attack without good reasons. Oh, and if you’re trying to intimidate me, you’ll have to try a lot harder. I’ve seen things that will make your worst nightmares look like the sweetest daydreams. In fact, they’d drive almost anyone to insanity.”  
“I can make you see your worst fears,” the girl said.  
“Whoop-de-bloody-doo. I’ve come across a creature that does the same thing. Now do me a favor and bugger off.” She closed her eyes to the shock of the siblings.  
The next couple weeks passed in a similar manner. The siblings would try to intimidate or threaten Ariadne. She would either brush them off or simply ignored them. Strucker left her alone at the insistence of Dr. Lisk who wanted her to recover from the initial experiment before they did any further testing.  
Ariadne sat on her cot picking at loose threads in the blanket. “Well, well… What do we have here? Agent Black,” a voice said from the other side of the glass.  
“Agent Ward,” Ariadne said surprised. Her eyes widened and then narrowed. She rose from her cot and stalked over to the glass. “You’re Hydra.”  
The siblings looked over, curious as to what was going to happen. No matter what they’d said to her, they’d never gotten this kind of reaction from her.  
“Well you certainly figured it out faster than Coulson and his posse,” Ward said. “It took them witnessing my betrayal to realize I wasn’t loyal to S.H.I.E.L.D. Of course, your position does give you an advantage.”  
“You treacherous bastard,” Ariadne snarled, punching the glass. Flames blossomed around her fist and licked their way up her arm.  
“Temper, temper,” Ward scolded. “Enjoy our hospitality, Agent Black.” He walked away.  
Ariadne stepped back staring at the fire. She sat on the edge of her cot as the flames died away. She chuckled. “Oh, I’m never going to live this down if they ever find out.”  
“Who?” the male asked. “The Avengers?”  
“No, though they probably will make no end of jokes since my codename is Phoenix,” Ariadne said. “No some old friends of mine...” She trailed off into old memories.  
“What is Hydra?” the young woman asked.  
“Hydra was the Nazi’s deep science division,” Ariadne said. “We thought it was eradicated back at the end of the Second World War. Turns out it went underground and grew like a parasite inside of S.H.I.E.L.D. It’s who Strucker really works for.”  
“This is a S.H.I.E.L.D. operation,” the speedster said.  
“Hydra,” Ariadne corrected. “S.H.I.E.L.D. was dismantled after we learned that many agents were actually loyal to Hydra. If this was a S.H.I.E.L.D. operation, do you honestly think I’d be locked in here?”  
“It doesn’t matter. Our goal is the same.”  
“And what is that goal? Taking out the Avengers? Why? If it’s because of something Strucker convinced you of, he’s Hydra, Hydra lies.”  
“We were eating dinner the four of us,” the boy said. His sister tried to stop him, but let him continue when she felt the honest curiosity from Ariadne. “When the first shell hits, two floors below, it makes a hole in the floor. It’s big. Our parents go in, and the whole building starts coming apart. I grab her, roll under the bed and the second shell hits. But, it doesn’t go off. It just… sits there in the rubble, three feet from our faces. And on the side of the shell is painted on word…”  
“Stark,” his sister said.  
“We were trapped two days,” he said.  
“Every effort to save us, every shift in the bricks, I think, ‘This will set it off.’ We wait for two days for Tony Stark to kill us.”  
“I’m sorry,” Ariadne whispered into the silence. “You shouldn’t have had to lose your parents like that and so young too. I’m sure you don’t want to hear what I’m going to tell you, but I’m saying it anyway. Yes, Tony Stark made weapons and can be an arrogant bastard. He wasn’t the one who fired the bomb that killed your parents.”  
She shrugged. “Anyway, believe me or don’t. It’s up to you. Whoever’s proved right can say ‘I told you so,’ if they want. But if you take anything away from what I’ve just told you, remember this, in your quest for revenge, two graves must be dug. One for the person you’re seeking revenge on and the second for the person you used to be. Trust me, I’ve seen good friends destroy themselves to get their revenge.”  
After a few minutes of silence, Ariadne sighed. “Look. We’re going to be stuck together for the foreseeable future, so it would be nice if we could at least try to get along. Why don’t we start over? I’m Ariadne Black, though most people who know me call me Ari.”  
The siblings held a silent conversation between themselves. They came to a decision and introduced themselves as Pietro and Wanda Maximoff.  
Over the next few months the three of them worked on developing their gifts. Pietro could move so fast that all anyone could see of him was a blue and silver blur. Wanda, Ariadne found out, was both telepathic and telekinetic. She hadn’t tried to access Ariadne’s mind yet, but she made sure to strengthen her Occlumency shields. With practice, Ariadne found she could summon and manipulate fire in various sizes and intensities. The more intense or bigger the flames, the faster she tired, but Ariadne believed that in time she wouldn’t be as exhausted using her powers. She also learned she could use her fire to heal injuries after Stucker had tried to get information about S.H.I.E.L.D. and the Avengers out of her.  
One day, Ariadne became dizzy and would have fallen over if Pietro hadn’t caught her. Dr. Lisk didn’t know what was wrong with her, only that she wasn’t contagious, had a dangerous fever, and was drifting in and out of consciousness. When she was conscious the fever made her delirious. Pietro and Wanda were surprised to find themselves genuinely concerned for Ariadne as her condition worsened to the point where she wouldn’t wake up at all, her breathing became labored and her pulse slowed.  
While her body struggled to overcome the fever, Ariadne found herself in spirit form again, this time in a study that looked like it belonged in a mansion.  
“Well, I must say this is an interesting development,” a deep voice said from behind her.  
“Hello, Stephen,” Ariadne said as she turned and recognized the tall man with greying temples, dark hair, and deep red cloak as an old friend.  
“What are you doing here?” Dr. Strange asked.  
“No idea,” Ariadne said. “One moment I’m suffering from a fever in Sokovia and the next I’m here. This is the second time I’ve found myself in another country floating around as a spirit. I have no idea why and it’s vexing me.”  
“What was happening to you the last time this occurred?” Strange, ever the scholar, asked.  
“I was being turned into Strucker’s guinea pig, which could have killed me.”  
“I see. It seems because you were dead for six months, that whenever you are dying, your spirit separates from your body.”  
“Great,” Ariadne drawled.  
“This could be a fortunate happenstance.”  
Ariadne was going to ask what he meant when she heard the fluttering of wings behind her. She spun around to see a brunette man standing there. “Who are you?”  
He took a lollipop out of his mouth. “Gabriel.”  
She made the connection between his name and the three pairs of golden wings that were visible until he pulled them into his back. “The Archangel? God’s Messenger?” she asked, stunned.  
“You’re a sharp one,” Gabriel said, applauding.  
“So, why is my presence here a good thing?”  
Dr. Strange proceeded to tell her a story and his plan. Both he and Gabriel insisted multiple times that she didn’t have to help if she didn’t want to. She agreed to help despite knowing Strange said things the way he did to manipulate her into helping and that the pair of powerhouses were vague on both why they themselves couldn’t do the job and why it needed doing.  
Ariadne returned to Strange’s mansion when she completed her mission. She couldn’t find out the end of their plan as her spirit got pulled back into her body when she reentered the study. She came to in her Sokovian cell with a rattling cough.  
“Look who’s finally awake,” Pietro said.  
“Watch it, Speedy,” Ariadne rasped. “That almost sounded like you cared about the wellbeing of an Avenger.”  
With a flick of her fingers, Wanda prevented her from sitting up. “You’ve been delirious and unconscious for over two weeks. You aren’t going anywhere.”  
Strucker chose that moment to enter the room for his and Dr. Lisk’s daily check on Ariadne’s condition. “Well I see you’re recovered now,” Strucker said. “Just in time too. Your new accommodations are complete.” He yanked Ariadne up off her cot. His viselike grip on her upper arm was the only thing keeping her on her feet. “Let’s go.”  
Ariadne landed on the floor of her new 6’ x 8’ cell. The two henchmen slammed the steel door behind her. She pressed her hand against a fresh cut on her abdomen to stem the bleeding. Strucker hadn’t taken her straight to the cell. Instead he tried again to get information from her. He’d hoped that her weakened state would make it easier to break her. He was wrong.  
Pulling herself up onto her new cot, she looked around the room. It wasn’t much different from the one she’d shared with Pietro and Wanda except this one was smaller and the concrete walls were covered in what looked to be several layers of fire-retardant materials. They were probably what made it take so long for the cell to be ready.  
She sighed in annoyance. It didn’t seem like she’d be getting herself out of there anytime soon. Ariadne hoped the Avengers would hurry up and get their asses to Sokovia. They were looking for the scepter so they would have to learn it was here at some point.

**Notes for the Chapter:**

> I've got the first eleven chapters or so already written so I'm going to try to update about once or twice a week depending on how busy my schedule becomes when I start back at college. Thanks for the response so far and I'll be back soon.


End file.
